Steam-boiler



(No Model.)

'J. A. CALDWELL. STEAM BOILER.

No. 459,742. Patented Sept. 22, 1891.

WITNESSES INVENTOR W e). 3% a.amm;u.

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UNITED STATES PATENT OFFICE.

JOHN A. CALDWELL, OF BAY RIDGE, NEIV YORK.

STEAM-BOILER.

SPECIFICATION forming part of Letters Patent No. 459,742, datedSeptember 22, 1891.

Application filed July 24, 1890. $e1ialN0-359,847. (No model.)

T0 at whom it may concern:

Be it known that 1, JOHN A. CALDWELL, a citizen of Great Britain,residing at Bay Ridge, county of Kings, and State of New York, haveinvented a certain new and useful Improvement in Steam Boilers of theForm Known as VVater-Tu be Boilers; and I declare the following to be afull, clear, and exact description of the same, reference being had tothe accompanying drawings, which form a part of this specification.

My invention relates to improvements in sectional steam-boilers, inwhich- Figure 1 is a longitudinal side elevation showing thefurnace-walls in section, and Fig. 2 is a front elevation of the same.

These improvements will become more ap parent after the followingexplanation.

In other sectional steam-boilers the headers A B C D are all united inone piece. The result is annoyance from breakage caused by the unequalexpansion of the tubes. To cut this header into four pieces and nipplethese together so as to make a continuous waterway from the tubes to thesteam and water drum was an improvement over the solid one piece header,since instead of breaking it yields at the point of jointure.

Established practice has decided that the number of tubes one above theother shall be eight, (8,) and that the horizontal rows of 7 tubes shallnot be placed immediately above each other, as I have shown them, but ina staggered position, so that the hot gases as they pass up through thespaces of one row shall encounter the tubes of the next row, so as toretard them somewhat and divert them hither and thither.

To cut the header into four pieces and join them by nipples and at thesame time retain the staggering effect called for, headers or boxescontaining three tubes, which were triangular in shape, or boxescontaining four tubes which were rhomboidal in shape, or, if five tubeswere put in a box, the shape became like an hour-glass, &c. The reasonthat not less than three tubes to one box were used was because room hadto be allowed to work a ratchet-expander from the opening in front withwhich to expand the nipples into place. The objection to three tubes ina box arranged in a staggered position is that the water from twelvetubes has to pass through one nipple where it connectsto the steam andWater drum, there being only room for one nipple in the small end of thetriangle. With the rhomboid, containing four tubes to a box, the case isworse, for the water from sixteen tubes must go through the nippleconnecting to the drum. While the top and bottom sides of the rhomboidare long enough to allow for two nipples, the fact that they have tostand past each other to give the stagger to the tubes, as alreadyexplained, made it impossible heretofore to put in more than one nippleof equal diameter with the tubes, and to make thenipple larger than fourinches diameter, so as to increase the area of the water way, wouldrequire a special costly tube-expander to go with each boiler, whilefour-inch tubes and four-inch expanders are regular market sizes.

My improvements will now be plain. By placing the rows of tubes aboveeach other and not staggering I secure boxes or headers of quadrangularshape, which stand exactly over each other. Hence there is room for twonipples of the regular commercial size, which secures a regular-sizednipple entering the drum for each eight tubes instead of each twelve orsixteen tubes, as in the cases explained above; and to retain thestaggering effect and baffle or retard the hot gases, I place pieces offire-brick or other material between substantially each alternate row oftubes, thus getting free circulation, a staggered direction to thegases, and a flexible header all in one boiler. This has not beenaccomplished before. Incidentally I gain very free access to the tubesby the unscrewing of four nuts and a better adjustment of bolts forholding on the header-covers.

In this class of boiler the fuel is burned 011 the grate E, the hotgases pass upward among the tubes, (which are surrounded by brick wallsin the usual way,) then downward through the space F and upward againthrough the space H and out to the chimney. The water within the tubescirculates from the lower portion of the tubes toward the higher, thenceto the steam and Water drum, along the drum to the back end and down thetubes I, there being one for each vertical row of tubes. All the boxesor headers are nippled to each other by the nipples J J J J, and to thedrum by the nipples K. The tubes I are practically long nipplesconnecting the header D to the drum in the same Way as the short nipples.T J connect the headers -L to the drum in front.

I do not confine myself to the special shape of fire-brick or othermaterial shown between the tubes. It may be shaped like a common brick,placed with the corner down, and enough of them placed on end to makewhatever length is necessary; or a single thin plate of material may beplaced on top long enough to reach from tube to tube. I do not confinemyself to solid material, but it may be perforated, as shown at N, toallow the gases to partially pass through the obstructed space; or thesides of the bricks may be corrugated or notched, as at P, so as not tobear upon the tubes their whole length.

Having fully described my inventiomwhat I claim, and desire to secure byLetters Patent, is-

In a water-tube boiler, the combination, with a series of tubes arrangedquadrangularly to each other, the sides of said quadrangles beingarranged in horizontal and V61" tical planes, of fire-brick or othermaterial disposed so as to bridge the space between substantially eachalternate pair of said tubes for the purpose of giving a staggeringdirection to the hot gases.

I11 Witness whereof I have hereunto subscribed my name in presence oftwo subscribing witnesses.

JOHN A. CALDWELL.

\Vitnesses:

ROBERT I-IUTcPnNsoN, S. P. HU'rcHINsoN.

